Cellular telephony products have been distributed to consumers in substantial numbers. The most common cellular telephony products are cellular telephones. In the United States, two cellular telephony standards are typically utilized to define the operations of cellular telephones. First, a time division multiplexing/time division multiple access (TDM/TDMA) cellular standard is defined by Telecommunications Industry Association/Electronics Industries Alliance (TIA/EIA) standards IS-41 and IS-136. Second, a code division multiple access (CDMA) cellular standard is defined by the TIA/EIA standard IS-95. Both standards define various physical layer requirements and public interface protocols to allow cellular subscribers to access the respective cellular networks.
Cellular telephones (both TDM/TDMA- and CDMA-compliant telephones) are assigned a respective Electronic Serial Number (ESN) and a Mobile Identification Number (MIN). The ESN is a unique 32-bit serial number used to uniquely identify a cellular telephone. The MIN may be the cellular telephone's phone number.
Since cellular networks allow subscribers to access the network from practically any location, cellular networks employ various security algorithms to prevent unauthorized cellular network use. Specifically, cellular networks utilize service control points (SCPs) to implement the security algorithms. An SCP is a remote database within a Signaling System 7 (SS7) network. SCPs are typically used in many cellular systems to implement home location registry (HLR) functionality. The HLR functionality maintains a database record for each cellular device to control interaction with the cellular network. The database records may indicate whether cellular devices are permitted to access a network. The database records may also indicate whether cellular devices are currently active within a network and may identify the respective locations of cellular devices within a network to facilitate routing of data to cellular devices.
When a cellular telephone attempts to access a cellular network to, for example, register in the network to receive calls, the cellular telephone transmits the ESN and the MIN to the local telephony switch. The local telephony switch utilizes the MIN to determine the cellular provider associated with the cellular telephone. The local switch then transmits the ESN by SS7 messaging to the cellular provider that maintains the respective HLR. The SCP determines from the ESN whether the cellular telephone is a valid device. If it is, the SCP transmits an appropriate message to the local switch and the local switch allows access to the cellular network. If the device is not valid, the SCP transmits an appropriate message to the local switch and the local switch denies access to the cellular network.
When a cellular device is stolen, the owner of the cellular device may contact a customer service representative or an automated system of the cellular provider. The owner may provide the MIN of the stolen device. The cellular provider will update its records in its HLR to indicate that the device associated with the corresponding ESN is not valid. Accordingly, any individual who attempts to utilize the cellular telephone will not be allowed to access any cellular network, although the stolen device remains operational. By utilizing the security protocols of cellular networks, the incentive to steal cellular telephones is significantly reduced.
However, this approach is problematic for other wireless devices. Specifically, a cellular telephone has essentially no other purpose other than accessing a cellular network. However, many commercially-available wireless and cellular devices perform a variety of functions. For example, wireless personal data assistants (PDAs), such as the Hewlett-Packard Company's Jornada 560 PDA, are capable of executing a variety of business, multimedia, and entertainment applications in addition to being able to perform wireless communications. If the security protocols of traditional cellular telephones were applied to wireless PDAs, an individual that has stolen a wireless PDA could not use the PDA for wireless communication. However, the individual could use the PDA to execute a large variety of other software applications.
Additionally, various security algorithms have been applied to protect stolen personal computers from unauthorized use. For example, many personal computers require a password to utilize various user applications. The password may be required from a boot-up script. Alternatively, the password may be required from a “screen-saver” process that is initiated when a user fails to enter data for a given period of time. However, both of these password requirements are generally ineffective. First, most users find password requirements cumbersome and intentionally disengage these features. Additionally, the password requirements may be overcome by booting a personal computer utilizing a system disk (e.g., a floppy disk) that does not invoke the password script or by resetting the personal computer depending upon how the password functionality is implemented.